1. Field of the Invention
The present invention relates to pipeline repair clamps. More particularly, the present invention relates to fabricated steel lug pipeline repair clamps.
2. Description of the Related Art
Repair clamps for easy repair of leaks developed in pipes are widely used for at least temporary repair. Such designs typically include a sealing gasket with an encircling band of steel held at either end by a tightening device. Prior designs capable of maintaining a seal in an industrial environment without bunching of the sealing gasket suffer from one or more shortcomings, such as the ability to maintain a secure grip on the steel band when tightened. These designs typically employ overlapping lugs, one having a base bearing at least one tension bar and one having a base bearing tightening bolts, each having a main body incorporating grippers mechanically pressed closed over the respective ends of the steel band during assembly, resulting in fractures in the grippers which eventually fail. Prior designs require substantial clearance for installation, which may not be available around an installed pipe. Prior designs that provide acceptable sealing are relatively costly to construct. It would be desirable to provide a low profile tension bar and tightening bolt lug-type pipe repair clamp which is effective, simple in construction, and inexpensive to construct.
U.S. Pat. No. 3,175,267, issued Mar. 30, 1965, to Graham describes a pipe clamp having a tightening assembly and a metal band with opposite folded ends. The folded ends are inserted and extended beyond the jaws, each end being bent down to form a locking tab against the jaws, thereby preventing any movement or slippage of the band when a tightening force is applied.
U.S. Pat. No. 3,195,205, issued Jul. 20, 1965, to Morriss, Jr., et al. describes a pipe clamp having a hardened silicon carbide grit in the recesses of the jaws to firmly hold the folded ends of the metal band and to prevent the band from movement during the application of a tightening force.
U.S. Pat. No. 3,692,062, issued Sep. 9, 1972, to Dunmire describes a pipe repair clamp wherein the ends of the band are welded to the lug base portion using spot weld and plug welds.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus, a fabricated steel lug repair clamp solving the aforementioned problems is desired.
The present invention is a fabricated steel pipe repair clamp having a steel band and interlocking steel lugs having respective tension bars and tightening bolts or studs forming the tightening assembly. The tightening assembly comprises a welded stud lug assembly, and a tension bar lug welded assembly, each having a base plate, and a backup plate. The two folded terminals of the clamping metal band are welded between the base plate and the backup plate forming the respective lug bodies. The laminated weld forming the lug assembly results in a stronger lug body backup plate and provides an even clamping force. An alternative embodiment combines the base plate and the backup plate connected to form jaws. Yet another embodiment employs only backup plates to form the lugs, the backup plates being offset to receive the respective band ends being located between the backup plate and the tensioner bars and between the studs and their backup plate, respectively.
Accordingly, it is a principal object of the invention to provide a pipe repair clamp with is simple in design, low in profile, and sturdy in construction.
It is another object of the invention to provide a pipe repair clamp as above having fabricated steel lug bodies.
It is a further object of the invention to provide a pipe repair clamp as above wherein said fabricated steel lug bodies are sandwiched base plates and a backup plates with respectively folded over steel band ends welded therebetween.
Still another object of the invention is to provide a pipe repair clamp as above wherein the base plate and the backup plate are connected, forming a jaw.
Yet another object of the invention is to provide a pipe repair clamp as above wherein the base plate and the backup plate are a single plate offset so as to form band end receiving grooves with respective tensioner bars and tightening studs.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.